Due to the high-capacity utilization of the A7 interstate, with up to 150,000 vehicles daily, a decision was made to expand the section between the Elbtunnel and the Schleswig-Holstein state border in 2007. Instead of four lanes, this section will have six or eight lanes. Extensive noise shielding measures will be implemented to protect local residents. The section is divided into three construction phases. The 3.6-kilometre Schnelsen segment is covered over 565 metres as a two-line tunnel using the cut-and-cover method. Noise barriers more than eight metres high and projecting far out in some sections, were constructed along seven kilometres of the interstate in total. The project also required the demolition of ovepass structures as well as reconstruction and adaptation of further infrastructure. The tunnel was designed as a water-impermeable concrete structure with deep foundations using drilled piles. The concrete cover is around a metre thick. A backfill with 1.2 metres of soil forms the basis for its complete greening, while an idyllic allotment complex is to be developed on some sections. Traffic flow had to be maintained throughout the entire construction period.